If you’re a pediatric SLP and you’ve been following the posts about my collaboration with a colleague about a phonology case, then you probably already have a good idea of what I mean by ‘the chart.’ I’m talking about the chart published by Sander (1972). You can access the full article here. Unfortunately, due to copyright issues, it’s behind a paywall.
But, ‘the chart’ itself is available online:
If you’re using this chart to justify waiting to intervene, then – quite frankly – you’re doing it wrong and you’re doing your clients a disservice. That’s especially true if you use this chart to wait an additional year or so from the right edges of each bar to intervene.
First, if you read the very short article that goes with this chart, you learn that Sander himself was arguing for something he called “customary age of production.” That’s when 51% of kids are producing a given phoneme in 2 of 3 word positions. Customary age of production is represented by the left edges of each bar. The length of each bar is representative of the variability in acquisition from customary age of production on the left to the age of mastery (where 90% of kids produced the sound correctly 100% of the time across all word positions) on the right.
Secondly, Sander didn’t collect his own data. He summarized data from the 1930s, 1950s, and 1960s. That’s right, some of the data were already nearly 50 years old when he wrote this article in 1972. Now, some of these data are nearly 100 years old. Those data happen to be the data on the age of mastery – or the right ends of the bars. In you were wondering, the most recent attempt to determine when speech sounds are learned is now 30 years old (Iowa-Nebraska Norms Project; behind a paywall)
Like technology, language isn’t a static thing. Things change. And, the ubiquity of technology may be causing greater language change to happen more quickly. Does it bother anyone else that many SLPs are basing treatment decisions on data that are nearly 100 years old? I hope so. Because disruption = change = progress!
What to do instead? My recommendation is focus on the phonemes a child excludes from their phonological system. If you have the choice, spend the client’s and your time working on the phonemes the child has not yet acquired in any word position. Then, treat the unknown phoneme in the most linguistically marked position. If a phoneme is emerging in 1 word position, it’s on its way in. Leave it alone. You’ve got bigger fish to fry first. If you find yourself needing to refer to ‘the chart’, then look at the left edges of the bars first.
I’ll address and hopefully bust the myth of stimulability as a factor in treatment target selection in a later post.